Introduction

TWAIN is a standard for image input devices, such as scanners and digital cameras. Getting an image from a TWAIN device can be very simple. First, there is a standard facility for selecting the input device. It is similar to selecting a default printer, and you can skip this step if you know that the default is right. Then, each TWAIN device has its own user interface, which you invoke to acquire an image.

Some complexity is introduced only when acquiring multiple images or when bypassing the user interface. If you acquire multiple images, you must code a callback function or event procedure to handle each image. If you bypass the user interface, you must set some standard TWAIN parameters to provide the information that the TWAIN driver would normally get from the user interface. The tricky part is that some TWAIN drivers implement the standard more fully than others. If you do not know in advance how the TWAIN device will behave, it is a good idea to add logic to your program to test the success of setting the TWAIN parameters. LEADTOOLS provides properties, methods and events for all of this.

Please note that TWAIN support requires TWAIN.DLL for 16-bit or TWAIN_32.DLL for 32-bit. These files must be obtained from the TWAIN device manufacturer.

The basic LEADTOOLS TWAIN VCL features are available in all LEADTOOLS toolkits. The Fast Configuration capabilities are available only in the LEADTOOLS Document Imaging, LEADTOOLS Document Imaging Suite, LEADTOOLS Medical Imaging and LEADTOOLS Medical Imaging Suite toolkits. These capabilities are locked and must be unlocked using the key obtained from LEAD. For more information, refer to Unlocking Special LEAD Features. The Twain capabilities can be used to:

$image\sqrblit.gif$ manage the TWAIN sources.

$image\sqrblit.gif$ acquire pages from a specified source.

$image\sqrblit.gif$ handle different TWAIN sources, like scanners, barcode readers, and digital cameras.

Executable demos are included in all LEADTOOLS products. The executable demos provide a quick and easy way to evaluate features and performance.

You can use the LEADTOOLS VCL in:

Delphi 4.0

Delphi 5.0

Delphi 6.0

Delphi 7.0

C++ Builder 4.0

C++ Builder 5.0

C++ Builder 6.0

Summary of All Supported Image File Formats

Please note that due to the large size of the PDF files that contain the LEADTOOLS manuals, these files are no longer included in the setup. Instead, these PDF files can be downloaded from our website at http://support.leadtools.com/SupportPortal/DesktopDefault.aspx?tabindex=3&tabid=27.